The lens-fitted photo film units are widely used because they are economical and easy to handle thanks to their simple photographic mechanisms such as a shutter mechanism and a film winding mechanism.
With the wide spread of the lens-fitted photo film units, a variety of film units adapted to many photographic scenes have been developed and sold, such as ones for night-view, ones for close-up shooting, ones for telephotography, and ones for sequential shooting. Recently, such film units that can switch over photography modes have been brought into the market. As such a film unit, an article named “Night & Day (a trade name)”, which is loaded with high-speed photo film of ISO1600 or more, is produced and sold by the present applicant.
Out of concern for environmental problems, a recycling system for the lens-fitted photo film units have already been adopted, whereby used-up film units are recovered after the development process in photo-labs by their own manufacturers, and are processed to be reproduced and sold as recycled film units. The production processes include sorting and disassembling film unit bodies, inspecting reusable parts, reassembling and reloading the lens-fitted photo film unit bodies. In order to reproduce film units with equal quality to new ones from used-up film units, it takes enormous cost for the inspection and repair of reusable parts, so that the recycling cost becomes equal to or even higher than the cost for manufacturing new film units.
To save the recycling cost, many solutions have been suggested. For example, the proportion of reusable parts of the lens-fitted photo film unit is raised by unitizing its components such as a lens mechanism and a flash device. Or the proportion of recyclable parts is raised by transforming plastic parts of the used film unit, such as front and rear covers, into pellets that are used as materials for forming these parts.
However, there is another factor that raises the recycling cost. As the last stage of recycling process of the lens-fitted photo film units, some of the lens-fitted photo film units as reassembled and reloaded with a new roll of photo film each, are picked up and subjected to a vibration test, a light leakage test, an actual shooting test and the like. Although such sampling is generally carried out also at the last stage of manufacturing new film units, the proportion of defective ones found by the sampling of the reassembled film units is higher than in the new film units. If any defect is found, the photo film loaded in the defective film unit is thrown away in vain. Especially where the defective film unit is loaded with high-speed film of ISO1600 or more, which is expensive in comparison with standard-speed film of ISO400 or so, such a waste of new photo film greatly increases the recycling cost of the lens-fitted photo film unit.